FTIR Study of Bacteriorhodopsin

细菌视紫红质（bR）是一种光驱动的质子泵， 功能包括两个关键的基于膜的过程， 运输和能量转换。 尽管有大量的研究， bR和其他膜蛋白，这些的分子基础 过程是未知的。 罗斯柴尔德博士的实验室开发了 一种基于傅里叶变换红外（FTIR）差分 光谱学允许这些过程进行研究， 单个蛋白质残基的水平。 这项工作提供了 关于质子化状态变化的信息， 在bR光循环过程中的特定残留物的环境。 的 本研究的目标将是利用这种方法来开发 bR泵机制越来越详细的图片。 这些 最近开发的改进方法将促进研究 对于时间分辨FTIR差谱，偏振FTIR 和衰减的全反射。 与Dr. H. G合作。 Khorana的小组开发了新方法，基于现场- 定向诱变，用于指定FTIR差异中的条带 光谱到个别蛋白质残基的振动。 这些 技术允许质子化序列的调查 bR质子中Asp基团和其他残基的变化 转运途径; bR α- 螺旋和变化中的个别COOH基团的pK 膜的 平行研究将使用时间分辨 紫外/可见光谱和共振拉曼光谱。 FTIR 对两种相关膜蛋白的研究也将继续进行 来自盐生盐杆菌（Halobacterium halobium）：盐视紫红质（halorhodopsin，hR），光驱动的 氯化物泵和感觉视紫红质（sR-I），一种趋光性光 受体的

Bacteriorhodopsin (bR) is a light driven proton pump whose function includes two key membrane based processes, active transport and energy transduction. Despite extensive research on bR and other membrane proteins, the molecular basis of these processes is unknown. Dr. Rothschild's laboratory has developed an approach based on Fourier transform infrared (FTIR) difference spectroscopy which allows these processes to be investigated at the level of single protein residues. This work is providing information about changes in the protonation state and environment of specific residues during the bR photocycle. The goal of this research will be to utilize this approach to develop an increasingly detailed picture of the bR pump mechanism. These studies will be facilitated by recent improved methods developed for time-resolved FTIR difference spectroscopy, polarized FTIR and attenuated total reflection. In collaboration with Dr. H.G. Khorana's group new methods have been developed, based on site- directed mutagenesis, for assigning bands in FTIR difference spectrum to the vibrations of individual protein residues. These techniques allow the investigation of the sequence of protonation changes of Asp groups and other residues in the bR proton transport pathway; changes in the orientation of the bR alpha- helices and changes in pK of individual COOH groups in the membrane. Parallel studies will be conducted using time-resolved UV/visible spectroscopy and resonance Raman spectroscopy. FTIR studies will also be continued on two related membrane proteins from Halobacterium halobium: halorhodopsin (hR), a light driven chloride pump and sensory rhodopsin (sR-I), a phototaxis light receptor.